Is it alright to use 5w50 oil in a stage 3 cossie ?

Been told off some people use 10w60 who have been told off NMS to use, who said that 5w30 is the quickest way to blow a cossie, and today been told that 5w50 is a good oil to use and is used by Harvey Gibbs in his big spec engines, which to me aint much more than 5w30.

Dont know what to use for the best when different people are coming up with different recomendations.